Question: There was a plate full of brownies. Tina ate $4$ of the brownies. There were $16$ brownies left. How many brownies were on the plate before Tina ate some?
Answer: We can use subtraction to find the missing whole: ${\Box} - {4} = {16}$ We can also add all of the brownies together: ${4} + {16} = {\Box}$ ${20}$ brownies